Quantum computing system and method for time evolution of bipartite hamiltonians on a lattice

Abstract

A method evolves a lattice of qubits in a quantum computer. The lattice of qubits includes a first plurality of qubits and a second plurality of qubits in the quantum computer. Each qubit in the first plurality of qubits is adjacent to at least one qubit in the second plurality of qubits. The method includes: (A) applying, in parallel, a first set of quantum gates between the first plurality of qubits and the second plurality of qubits to create a first set of entangled pairs of qubits; (B) after (A), swapping, in parallel, pairs of qubits, the swapping comprising: (B) (1) swapping pairs of adjacent qubits in the first plurality of qubits according to a first swap criterion; and (B) (2) swapping pairs of adjacent qubits in the second plurality of qubits according to a second swap criterion, wherein the second swap criterion differs from the first swap criterion.

1 . A method for evolving a lattice of qubits in a quantum computer, the lattice of qubits comprising a first plurality of qubits in the quantum computer and a second plurality of qubits in the quantum computer, wherein each qubit in the first plurality of qubits is adjacent to at least one qubit in the second plurality of qubits, the method comprising:
 (A) applying, in parallel, a first set of quantum gates between the first plurality of qubits and the second plurality of qubits to create a first set of entangled pairs of qubits;   (B) after (A), swapping, in parallel, pairs of qubits, the swapping comprising:
 (B)(1) swapping pairs of adjacent qubits in the first plurality of qubits according to a first swap criterion; and 
 (B)(2) swapping pairs of adjacent qubits in the second plurality of qubits according to a second swap criterion, wherein the second swap criterion differs from the first swap criterion. 
   
     
     
         2 . The method of  claim 1 , further comprising:
 (C) after (B), applying, in parallel, a second set of quantum gates between the first plurality of qubits and the second plurality of qubits to create a second set of entangled pairs of qubits.   
     
     
         3 . The method of  claim 2 , further comprising:
 (D) after (C), swapping, in parallel, pairs of qubits, the swapping comprising:
 (1) swapping pairs of adjacent qubits in the first plurality of qubits according to the second swap criterion; and 
 (2) swapping pairs of adjacent qubits in the second plurality of qubits according to the first swap criterion. 
   
     
     
         4 . The method of  claim 3 , further comprising:
 (E) after (D), repeating (A)-(D) until each qubit of a subset of the first plurality of qubits is part of an entangled pair with each qubit of the second plurality of qubits.   
     
     
         5 . The method of  claim 4 , further comprising:
 (F) after (E), measuring at least one qubit in the lattice of qubits to generate an output state.   
     
     
         6 . The method of  claim 1 , wherein the first set of quantum gates comprises a ZZ-interaction. 
     
     
         7 . The method of  claim 1 , wherein the first swap criterion comprises an even swap criterion. 
     
     
         8 . The method of  claim 1 , wherein the first swap criterion comprises an odd swap criterion. 
     
     
         9 . The method of  claim 1 , further comprising using a classical computer to control the quantum computer to perform (A) and (B), the classical computer comprising at least one processor and at least one non-transitory computer-readable medium having computer program instructions stored therein, the computer program instructions being executable by the at least one processor to cause the classical computer to control the quantum computer to perform (A) and (B). 
     
     
         10 . A hybrid quantum-classical computing system for evolving a lattice of qubits in a quantum computer, the lattice of qubits comprising a first plurality of qubits in the quantum computer and a second plurality of qubits in the quantum computer, wherein each qubit in the first plurality of qubits is adjacent to at least one qubit in the second plurality of qubits, the hybrid quantum-classical computing system comprising:
 the quantum computer, the quantum computer including a plurality of qubits and a qubit controller that manipulates the plurality of qubits, the plurality of qubits including the first plurality of qubits and the second plurality of qubits; and   a classical computer storing machine-readable instructions that, when executed by the classical computer, control the classical computer to cooperate with the quantum computer to perform a method, the method comprising:   (A) applying, in parallel, a first set of quantum gates between the first plurality of qubits and the second plurality of qubits to create a first set of entangled pairs of qubits;   (B) after (A), swapping, in parallel, pairs of qubits, the swapping comprising:
 (B)(1) swapping pairs of adjacent qubits in the first plurality of qubits according to a first swap criterion; and 
 (B)(2) swapping pairs of adjacent qubits in the second plurality of qubits according to a second swap criterion, wherein the second swap criterion differs from the first swap criterion. 
   
     
     
         11 . The hybrid quantum-classical computing system of  claim 10 , wherein the method further comprises:
 (C) after (B), applying, in parallel, a second set of quantum gates between the first plurality of qubits and the second plurality of qubits to create a second set of entangled pairs of qubits.   
     
     
         12 . The hybrid quantum-classical computing system of  claim 11 , wherein the method further comprises:
 (D) after (C), swapping, in parallel, pairs of qubits, the swapping comprising:
 (1) swapping pairs of adjacent qubits in the first plurality of qubits according to the second swap criterion; and 
 (2) swapping pairs of adjacent qubits in the second plurality of qubits according to the first swap criterion. 
   
     
     
         13 . The hybrid quantum-classical computing system of  claim 12 , wherein the method further comprises:
 (E) after (D), repeating (A)-(D) until each qubit of a subset of the first plurality of qubits is part of an entangled pair with each qubit of the second plurality of qubits.   
     
     
         14 . The hybrid quantum-classical computing system of  claim 13 , wherein the method further comprises:
 (F) after (E), measuring at least one qubit in the lattice of qubits to generate an output state.   
     
     
         15 . The hybrid quantum-classical computing system of  claim 10 , wherein the first set of quantum gates comprises a ZZ-interaction. 
     
     
         16 . The hybrid quantum-classical computing system of  claim 10 , wherein the first swap criterion comprises an even swap criterion. 
     
     
         17 . The hybrid quantum-classical computing system of  claim 10 , wherein the first swap criterion comprises an odd swap criterion.